Bump spring-boot-maven-plugin from 2.3.3.RELEASE to 2.3.4.RELEASE

Bumps [spring-boot-maven-plugin](https://github.com/spring-projects/spring-boot) from 2.3.3.RELEASE to 2.3.4.RELEASE.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v2.3.3.RELEASE...v2.3.4.RELEASE)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

samples/spring-boot-auto-config/pom.xml

@@ -73,7 +73,7 @@
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
-                <version>2.3.3.RELEASE</version>
+                <version>2.3.4.RELEASE</version>
             </plugin>
         </plugins>
     </build>

samples/spring-boot-plain/pom.xml

@@ -70,7 +70,7 @@
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
-                <version>2.3.3.RELEASE</version>
+                <version>2.3.4.RELEASE</version>
             </plugin>
         </plugins>
     </build>

spring-boot-starter/pom.xml

@@ -31,7 +31,7 @@
             <plugin>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-maven-plugin</artifactId>
-                <version>2.3.3.RELEASE</version>
+                <version>2.3.4.RELEASE</version>
             </plugin>
         </plugins>
     </build>